Transmission Rights of Way and Integrated Vegetation Management

What are Transmission Lines?

The majority of Pacific Gas and Electric Company's power lines are part of an electric distribution system which carries power ranging from 4,000 volts to 21,000 volts and distributes power to homes and businesses. The lines that carry electricity from power plants across the state belong to the company's transmission system. This system carries power from 60,000 volts to 500,000 volts. Because of the higher voltages, greater clearance is needed between vegetation and transmission lines than what is required between vegetation and distribution lines.

Vegetation Management of Transmission Rights-of-Way

Pacific Gas and Electric Company utilizes a program of Integrated Vegetation Management (IVM) to manage vegetation on transmission rights-of-ways. Properly maintained right-of-ways (ROW) are essential for the safety of the public and our workers. The long-term goal of our vegetation management program is to provide for public safety, worker safety, and environmental safety while providing for reliable service.

Establishing a Low Growing Plant Community

Pacific Gas and Electric Company’s goal is to convert tall growing plant communities in transmission right-of-ways to communities dominated by low growing plant species. By selectively controlling incompatible plants while preserving low growing grasses, herbs and woody shrubs we are able to accomplish our goal. With proper management, the low growing vegetation can eventually dominate the right-of-way and retard the growth of the tall growing vegetation, providing control of incompatible plants and reducing the need for future treatments. Studies show this type of meadow-like setting will enhance wildlife habitat by promoting vegetation preferred by birds, deer and other small animals.

Integrated Vegetation Management

The first step to creating a low growing plant community is to clear rights-of-way of tall growing and incompatible plant species. This is typically accomplished either mechanically or manually. Cutting or mowing alone is ineffective because it encourages the biological response of re-sprouting. After clearing, right-of-ways are monitored for re-sprouting and reinvasion by incompatible vegetation. Once this occurs, the right-of-way will be enhanced through various methods to provide the desired outcome of a low growing plant community. Many factors are considered before an appropriate method is chosen and implemented.

The Wire Zone Border Zone

The Wire Zone consists of low-growing shrub and grass communities directly under the transmission wires plus approximately 10’ on both sides. The Border Zone, which is the portion of the right-of-way that extends from 10’ outside of the wire to the edge of the ROW, is managed for taller shrubs, and brush plant community. This is the transition zone between the low-growing vegetation and taller.

Right-of-way transmission line zones